1. Field of the Invention
The present invention relates to a nonlinear element, an element substrate including the nonlinear element, and a display device including the element substrate. In particular, the present invention relates to a liquid crystal display device using a nonlinear element as a switching element.
2. Description of the Related Art
In recent years, it has been considered to use nonlinear elements for liquid crystal display devices. An MIM (metal insulator metal) switching element, which includes a three-layered structure formed by stacking a lower conductive thin film, an insulating thin film, and an upper conductive thin film, is known as one of the nonlinear elements.
As a conventional MIM switching element, a structure, as shown in FIG. 14, in which a lower conductive thin film 1002 is provided over a substrate 101 made from glass, an insulating thin film 1003 is provided over an entire surface, and an upper conductive thin film 1004 and a pixel electrode 1005 are provided thereover, is known (see the patent document 1). [Patent Document 1]: Japanese Patent Application Laid-Open No. Hei 7-7851
However, in a conventional nonlinear element using an insulating thin film, since the insulating thin film has high resistivity, it has been difficult to drive the nonlinear element at low voltage.
In addition, since an insulating thin film used in a conventional nonlinear element has different resistance depending on its difference in thickness of the insulating thin film, there have been problems such as variations in characteristics of the nonlinear element, and it has been necessary to make the thickness of the insulating thin film uniform. However, it is difficult to make thicknesses of insulating thin films used for all nonlinear elements uniform, and it takes a long time to make the thicknesses uniform. Thus, there has been also a problem of reduction in productivity.